Exposure tests have been conducted on small composite concrete beams. The beams, which are 508 mm long and have a square cross section of 102 mm, are strengthened with a steel plate 38 mm wide and 3 mm thick epoxy-bonded to one face. These have so far been exposed for up to 2 years at sites representing high rainfall, industrial and marine environments. Half the specimens were loaded during the exposure period and half were unloaded. Loading tests have been carried out on the weathered beams and the results compared with beams kept in a control environment of 20 deg c and 65 per cent rh. The results indicate that there is a small overall reduction in strength of the exposed beams after one and two years, compared with those kept under control conditions. This reduction in strength is likely to have been caused by corrosion of the steel plate adjacent to the resin. Although there is an apparent weakening of the bond between the steel and the concrete due to corrosion of the plate, the shear strength is still greater than that of the concrete. Further beams are to be tested after 5 and 10 years of exposure. (Author/publisher)
Abstract